科创中国

The active magnetic bearing(AMB)suspends the rotating shaft and maintains it in levitated position by applying controlled electromagnetic forces on the rotor in radial and axial directions.Although the development of various control methods is rapid,PID control strategy is still the most widely used control strategy in many applications,including AMBs.In order to tune PID controller,a particle swarm optimization(PSO)method is applied.Therefore,a comparative analysis of particle swarm optimization(PSO)algorithms is carried out,where two PSO algorithms,namely(1)PSO with linearly decreasing inertia weight(LDW-PSO),and(2)PSO algorithm with constriction factor approach(CFA-PSO),are independently tested for different PID structures.The computer simulations are carried out with the aim of minimizing the objective function defined as the integral of time multiplied by the absolute value of error(ITAE).In order to validate the performance of the analyzed PSO algorithms,one-axis and two-axis radial rotor/active magnetic bearing systems are examined.The results show that PSO algorithms are effective and easily implemented methods,providing stable convergence and good computational efficiency of different PID structures for the rotor/AMB systems.Moreover,the PSO algorithms prove to be easily used for controller tuning in case of both SISO and MIMO system,which consider the system delay and the interference among the horizontal and vertical rotor axes.

Current researches show that mechanical deformation of seal ring face makes fluid film clearance decrease at high pressure side, thus a divergent clearance is formed and face wear occurs more seriously at the high pressure side than that on the low pressure side. However, there is still lack of published experimental works enough to prove the theoretical results. In this paper, a spiral groove dry gas seal at high pressures is experimentally investigated so as to prove the face wear happened at the high pressure side of seal faces due to the face mechanical deformation, and the wear behavior affected by seal ring structure is also studied. The experimental results show that face wear would occur at the high pressure side of seal faces due to the deformation, thus the leakage and face temperature increase, which all satisfies the theoretical predictions. When sealed pressure is not less than 5 MPa, the pressure can provide enough opening force to separate the seal faces. The seal ring sizes have obvious influence on face wear. Face wear, leakage and face temperature of a dry gas seal with the smaller cross sectional area of seal ring are less than that of a dry gas seal with bigger one, and the difference of leakage rate between these two sizes of seal face width is in the range of 24%–25%. Compared with the effect of seal ring sizes, the effect of secondary O-ring seal position on face deformation and face wear is less. The differences between these two types of dry gas seals with different secondary O-ring seal positions are less than 5.9% when the rotational speed varies from 0 to 600 r/min. By linking face wear and sealing performance changes to the shift in mechanical deformation of seal ring, this research presents an important experimental method to study face deformation of a dry gas seal at high pressures.

介绍了烧结生产自动配料控制系统的组成及工作原理.控制系统采用上下两级的计算机控制形式,并在系统的设计中,根据生产的实际情况采用了新的控制思想和控制方法.

主要针对一个单轴稳定平台控制系统进行研究、设计以及实现.稳定平台控制系统通过微机械陀螺实时采样,并对信息进行分析处理,输出控制信号到电机,使电机达到对平台姿态进行补偿的目的,使平台相对惯性空间保持方位不变.主要分析了系统工作原理和控制方法,对稳定平台硬件和软件进行了设计,并用MATLAB进行了控制算法仿真,选择PID方法进行了校正.

目前,工业工程广泛应用非线性的PID控制、时滞特色、强耦合,控制效果不理想.虽然优化PID控制,自适应PID控制和非线性PID控制和PID控制的其他改良形式,但在根本的意义上说,PID的参数只能为满足生产过程控制目标的某一方面要求而整定的,使控制效果达不到最佳.对于许多复杂庞大的被控对象,有时难以建立有效的数学模型,模糊控制就应运而生.模糊控制就是利用模糊集合论,仿照人的模糊控制策略转化为计算机所能接受的控制算法,进而实施控制的一种理论和技术.

以数控系统的伺服电机控制为例,使用ARM微处理器芯片设计与实现软PLC,在此PLC的基础上,结合模糊控制理论和PID控制算法,通过MATLAB仿真完成参数整定,设计了以个基于模糊PID算法的电机控制系统.该系统不仅应用于数控系统,也可用于其它行业的电机控制.

针对火电厂过热汽温对象的大惯性、大迟延、时变、不确定的特点,基于一阶加纯滞后模型,将一种改进的内模PID控制方案应用于火电厂过热汽温的控制,并给出了设计步骤及各参数在线计算公式.该方案结构简单,易于在DCS中组态实现.对某超临界600 MW直流锅炉过热汽温系统4种典型工况进行仿真控制表明了该方法的优越性,其过渡过程时间短,无超调,适用于大惯性、大迟延过程的控制,控制效果明显优于串级PID控制,具有较强的鲁棒性和自适应能力.

针对稳定跟踪平台控制系统实时性强、抗干扰能力强、鲁棒性好的要求,设计了一种串并联两级稳定跟踪平台,提出了一种模糊控制和传统PID控制相结合的模糊-PID控制算法,比较了针对微分的改进PID算法和基于模糊理论的PID控制算法,并给出了基于MATLAB/Simulink的实现方法和仿真.通过仿真表明,采用模糊-PID控制算法有更好的控制效果.

在实现高频高压型电子辐照加速器控制系统的分布式控制(Distributed Control System,DCS)的基础上,设计了一个以可编程逻辑控制器(Programmable Logic Controller,PLC)为控制核心,以小脑模型神经网络与PID(Cerebellar Model Articulation Controller and Proportional-Integral-Derivative,CMAC-PID)为主要控制算法的束流路径自动校正系统.实验表明:CMAC-PID控制器的调节速率和稳定度相比常规PID控制器均有较大提升,保证加速器在束流路径发生偏转时能快速稳定地将束流自动校正到芯管中间位置.

为了提高高速列车速度控制的跟踪精度,解决传统PID控制因为参数固定不变而导致的控制不灵活,停车精度不高的缺点,以CRH2-300的数据为例计算了列车牵尹几制动的理恕运行曲线,并结合模糊控制、PID控制和预测控制各自的优点,在传统的PID控制中加入模糊控制,实现了根据实际的系统状况对PID控制器的参数进行在线调节,同时引入预测控制达到提前调整的目的,设计了适合高速列车速度跟踪控制的顽测模糊PID控制器,控制高速列车跟踪理想运行曲线,并与模糊PID以及传统的PID控制结果作比较.仿真结果表明该控制器能够比模糊PIDu2及传统的PID控制更有效的跟踪目标曲线,满足误差小、鲁棒性高的要求,并在很大程度上提高了列车的停车精度.